From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 212C248C402; Thu, 7 May 2026 20:22:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778185370; cv=none; b=iNUdyVOLB/DMTfQ6JUw1q+jo1FOhDpsVrQcdOQA8OYSfVOpZrDn4/rLlwehHHtNmFUsu0jmnI9xkOma/V5Q8tyeHU2fI1J+x8Zg8J8bA8BSygRbYGRyqPR0eZhRG4SELTmEj3X2fHG9mc9ULLaEkneg5pEz7r0M1VuyPTHMmtV4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778185370; c=relaxed/simple; bh=N5R9oRhQJzT3W0fySZmS/tE/RBQSqt6xZpQf/jxTvVM=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=joDYIhyWf+EbAOR6nuZc5+f2xo78ErDAZ3zfD/XSzf/Gt9BROHmchiRyQt4QXFOO38Il0i8fmhe/iGnEBzK+EdatwdZuHeKEdwnNtS0kgwDMSzlx92VN9N5i/OSseeH/PduJnQLtD/rTtGDaRR04V0N2amEcClFrmW97S3o4wSo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mA71HU68; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mA71HU68" Received: by smtp.kernel.org (Postfix) with ESMTPS id 06256C2BCB8; Thu, 7 May 2026 20:22:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778185370; bh=N5R9oRhQJzT3W0fySZmS/tE/RBQSqt6xZpQf/jxTvVM=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=mA71HU68Fqq043Dg3G3uzdUgSs9zZvLZh3+sEbK/2klQoFnTXmERKQKyQVi4kYpnp FzBAJlY5hhFPmEANZN8gAaN1cm9D/PVdlCmJKaaWvoMLc0qb+sqTrz970mgWgiyaoz 6oHOfIeao1HbOUPcpB8b0malnCNXc7XV8AOXY4BuvAIb7rn2XxDRsuvLfrQRh2/VHa r3LptC9AO4t3QR+xTjAo6UIVY47Bjkn5zWd1fe2hWbf4jNMLme2JamPFr5VouA22bK TBEGUujvUPz1z44+k7g8qvApNY0AJuebvE1okJPlUZR72/DFT77qddkdeYTP1BtGPm 61nyCc4PLSoMQ== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC558CD379F; Thu, 7 May 2026 20:22:49 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Thu, 07 May 2026 13:22:32 -0700 Subject: [PATCH v6 13/43] KVM: guest_memfd: Return early if range already has requested attributes Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260507-gmem-inplace-conversion-v6-13-91ab5a8b19a4@google.com> References: <20260507-gmem-inplace-conversion-v6-0-91ab5a8b19a4@google.com> In-Reply-To: <20260507-gmem-inplace-conversion-v6-0-91ab5a8b19a4@google.com> To: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, ira.weiny@intel.com, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, tabba@google.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Jason Gunthorpe , Vlastimil Babka Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1778185365; l=2558; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=b2U3rQZtoe13iK85Md2FTyXx66OuI05q1gqdIbbHlSQ=; b=UN/8Y1orfcMwyEZH0S6RExPannjH51GfhVxr5vzN7x9jmFkjvni9/PmzSMTOUzMaLZLxQCqVH lSEBC+HA0RABt69qVqqsoI+XK5xrvF6Ruy0bRDp9YiSgwEBHz9IOKpv X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com From: Ackerley Tng Extract a helper out of kvm_gmem_range_is_private() that checks that a range has given attributes. Optimize setting memory attributes by returning early if all pages in the requested range already has the requested attributes. Signed-off-by: Ackerley Tng --- virt/kvm/guest_memfd.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index baf4b88dead1f..034b72b4947fb 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -86,6 +86,23 @@ static bool kvm_gmem_is_shared_mem(struct inode *inode, pgoff_t index) return !kvm_gmem_is_private_mem(inode, index); } +static bool kvm_gmem_range_has_attributes(struct maple_tree *mt, + pgoff_t index, size_t nr_pages, + u64 attributes) +{ + pgoff_t end = index + nr_pages - 1; + void *entry; + + lockdep_assert(mt_lock_is_held(mt)); + + mt_for_each(mt, entry, index, end) { + if (xa_to_value(entry) != attributes) + return false; + } + + return true; +} + static int __kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot, pgoff_t index, struct folio *folio) { @@ -649,12 +666,15 @@ static int __kvm_gmem_set_attributes(struct inode *inode, pgoff_t start, pgoff_t end = start + nr_pages; struct maple_tree *mt; struct ma_state mas; - int r; + int r = 0; mt = &gi->attributes; filemap_invalidate_lock(mapping); + if (kvm_gmem_range_has_attributes(mt, start, nr_pages, attrs)) + goto out; + mas_init(&mas, mt, start); r = kvm_gmem_mas_preallocate(&mas, attrs, start, nr_pages); if (r) { @@ -1140,20 +1160,13 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_get_pfn); static bool kvm_gmem_range_is_private(struct gmem_inode *gi, pgoff_t index, size_t nr_pages, struct kvm *kvm, gfn_t gfn) { - pgoff_t end = index + nr_pages - 1; - void *entry; - if (vm_memory_attributes) return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + nr_pages, KVM_MEMORY_ATTRIBUTE_PRIVATE, KVM_MEMORY_ATTRIBUTE_PRIVATE); - mt_for_each(&gi->attributes, entry, index, end) { - if (xa_to_value(entry) != KVM_MEMORY_ATTRIBUTE_PRIVATE) - return false; - } - - return true; + return kvm_gmem_range_has_attributes(&gi->attributes, index, nr_pages, + KVM_MEMORY_ATTRIBUTE_PRIVATE); } static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, -- 2.54.0.563.g4f69b47b94-goog